1. Field of the Invention
The present invention relates to a support device for lining ditches. More particularly, it relates to such a support device having lining uprights which are held in place at a parallel spaced apart distance by braces and lining plates guided in or on the uprights by means of guide rollers.
2. The Prior Art
A support device is disclosed in German Patent No. 23 23 321 B2, where guide heads with guide rollers are provided at intervals along the height of the end faces of the lining plates. Some of the rollers are mounted with their bearing axes perpendicular to the plane of the lining plate. Other rollers have their axes in a plane between the lateral faces of the lining plate and perpendicular to the guiding uprights. The latter rollers run only along the leg of the section that is toward the inside of the ditch.
The purpose of this prior art patent is to allow the lining plates to move in the guiding uprights with minimal friction. However, it has been found that in practice this construction is not strong enough. An additional guide means with rigid flanges disposed transversely to the plane of the lining plate must also be provided. This is particularly necessary, because the guide rollers must necessarily roll with a great deal of play, and therefore the connection between the guiding uprights and lining plate is unstable. This is particularly the case when compact earth is present which does not directly pres against the lining device.
A ditch lining device is also disclosed in British Patent No. 2,172,029 which includes guide rollers on the end walls of the lining plates. However, these rollers roll exclusively on bearing axes which are perpendicular to the plane of the lining plate. The lining plate is guided against the pressure of the ditch wall in a form-interlocking configuration by means of rigid elements in the guiding uprights.